<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>/*内部样式*/
        h2{color: aqua}
    </style>
    <!--引入外部的css样式文件-->
    <link rel="stylesheet" href="my.css">
</head>
<body>
   <h1 style="color: rgba(9,206,234,0.6)">内联样式1</h1>
   <h1 style="color: rgba(224,20,195,0.33)">内联样式2</h1>
   <h1 style="color: green">内联样式3</h1>
<h2>内部样式1</h2>
<h2>内部样式2</h2>
<h3>外部样式1</h3>
<h3>外部样式2</h3>
<h3>原谅她1</h3>
</body>
</html>